1. Field of the Invention
The present invention relates to an error picture image data correction apparatus for correcting error data of the picture image signals outputted from a video camera etc. that employs a solid image capturing device. transmission and signal data processing are included in the picture image data of the audio visual apparatus such as a VCR, a video disk, a scanner and a camera, even though the error is about only one pixel, the picture quality may be remarkably deteriorated.
2. Description of the Art
When error data unintentionally generated in the process such as data transmission and signal data processing are included in the picture image data of the audio visual apparatus such as a VCR, a video disk, a scanner and a camera, even though the error is about only one pixel, the picture quality may be remarkably deteriorated.
Especially in case that the camera includes defective pixels in the image capturing device, the picture quality will be remarkably deteriorated because those error data are always generated and included in the output picture signals in the same fixed position corresponding to the defective pixels.
Especially in case that the camera includes defective pixels in the image capturing device, the picture quality will be remarkably deteriorated because those error data are always generated and included in the output picture signals in the same fixed position corresponding to the defective pixels.
In recent years, a solid image capturing device, especially a charge coupled device (hereinafter referred to as xe2x80x9cCCDxe2x80x9d) is widely used as an image capturing device. However, the CCD has difficulty in the manufacturing process. Defective pixels are easily generated in the CCD pixels. Therefore, it is difficult to achieve enough high yields in the current CCD manufacturing technology. Considering the manufacturing cost, even though a manufactured CCD has some defective pixels, it will be employed as a product with an error picture image data correction apparatus for correcting the error data corresponding to the defective pixels.
As the conventional error picture image data correction apparatus, the apparatus disclosed by the unexamined Japanese patent application Tokkai-Hei 9-284783 is known. FIG. 5 is a block diagram that shows the configuration of the error picture image data correction apparatus of the above-mentioned application. In FIG. 5, 100a, 100b and 100c are input terminals in which each digital video signal corresponding to each R, G and B color channel is inputted respectively, 5011, 5021 and 5031 are delay elements that delay the inputted R, G and B signal data from input terminal 100a, 100b and 100c for one data period, and the delay elements are composed of D flip flop. Each output signal of these delay elements 5011, 5021 and 5031 is inputted to the output switch circuit 111 and the selector 108 respectively. 5012, 5022 and 5032 are delay elements that delay the output signal data from the delay element 5011, 5021 and 5031 for one data period, and the delay elements are composed of D flip flop. 5013, 5023 and 5033 are adders for adding each R, G and B signal inputted from input terminals 100a, 100b and 100c and each output signal outputted from delay elements 5012, 5022 and 5032 respectively. 5014, 5024 and 5034 are amplifiers for amplifying the inputted signal value by xc2xd by the bit shift and outputting the amplified signal data. These delay elements 5011, 5012, the adder 5013 and the amplifier 5014 compose the average mean value calculation circuit 501 corresponding to the R channel. The delay elements 5021, 5022, the adder 5023 and the amplifier 5024 compose the average mean value calculation circuit 502 corresponding to the G channel. The delay elements 5031, 5032, the adder 5033 and the amplifier 5034 compose the average mean value calculation circuit 503 corresponding to the B channel. Each average mean value is inputted to the channel switching circuit 104. The delay elements 50115021 and 5031 not only compose the average mean value calculation circuit but also work for adjusting the phase of the input signal of the output switch circuit 111 to the predetermined phase.
The circuit 104 is a channel switch circuit for selecting color channel signals specified by the channel signal chj, chk and chl outputted from the control circuit 508 and outputting these selected color channel signals as sj, sk and sl respectively. Herein, the signal chk is a signal for specifying the defect channel which includes the defect error data. The signal sk is a defect channel signal, and the chj channel and the chl channel are the correct channels. The signal sj and sl correspond to these chj and chl channels. 105 and 106 are the adders for generating the differential signal Dj=skxe2x88x92sj, Dl=skxe2x88x92sl. 107 is a selector for selecting the smaller value between the differential signal value Dj or Dl according to the control signal cd outputted from the controller circuit 508 and outputting the selected smaller value. 108 is a selector for selecting one color channel signal among R, G and B channel signals according to the channel signal ch2 and outputting the selected color channel signal. 109 is an adder for adding the output signal of the selector 107 and the output signal of the selector 108. 110 is a clip circuit for outputting the output signal of the adder 109 as it is when the output signal level is within the predetermined range, and clipping the output signal of the adder 109 between the maximum value and minimum value when the output signal level is beyond the predetermined range. Generally, the peak level of the picture signal is set as the maximum value and the block level is set as the minimum value. The output switch circuit 111 can input each R, G and B input signal and the correction data Dc which is the output signal of the clip circuit 110 and can select one signal among the inputted data according to the chk which is the output signal of the control circuit 508.
Hereinafter, the operation of the conventional error picture image data correction apparatus configured above is described below. FIG. 4 is a drawing for explaining the input signals of the conventional error picture image data correction apparatus when the error picture image data is included in high frequency input signal data. In this example, the error picture image data is only one pixel data of high frequency input signal data included in the G channel. Herein the G channel data G(i) is a defective data wherein i represents time and t represents a certain time width, the average mean value output signal RAV, GAV and BAV shown respectively by Equation 1 are calculated in the average mean value calculation circuit 501, 502 and 503.
RAV={R(i+t)+R(ixe2x88x92t)}/2
GAV={G(i+t)+G(ixe2x88x92t)}/2
BAV={B(i+t)+B(ixe2x88x92t)}/2xe2x80x83xe2x80x83(Equation 1)
The channel switch circuit 104 outputs the average mean value RAV, GAV and BAV as the output signal Sj, Sk and Sl respectively. The adder 105 and 106 output the differential signal GAVxe2x88x92RAV, GAVxe2x88x92BAV as the output signal Dj and Dl. In this example, it is apparently understood from the signal level of each channel as shown in FIG. 4, the Dl is larger than Dj (Dj less than Dl). Therefore, the differential signal Dj is selected and outputted by the selector 107 according to the output control signal cd of the control circuit 508. The selector 108 outputs signal R(i) according to channel signal ch2, and the adder 109 generates signal Gxe2x80x2(i) shown by Equation 2.
xe2x80x83Gxe2x80x2(i)=R(i)+{G(i+t)+G(ixe2x88x92t)xe2x88x92R(i+t)xe2x88x92R(ixe2x88x92t)}/2xe2x80x83xe2x80x83(Equation 2)
Then, the clip circuit 110 outputs the correction data Dc, and the output switch circuit 111 replaces the error data G(i) with the correction data shown by Equation 2 and outputs the corrected data. The corrected data matches with the true value G(i) as shown in FIG. 4. Therefore, highly accurate error picture image data correction for the high frequency signal pattern can be achieved.
However, with the above-mentioned configuration, the conventional error picture image data correction apparatus can correct the error data appropriately only when there is only one error picture image data and the picture image data around the error picture image data are high frequency signal data as shown by FIG. 4. When there are plural error picture image data in the continuous plural pixels, the correction data will be generated based on the error picture image data. Therefore, an error correction data can not be achieved appropriately, this calculation error contained in the error correction data will work as noise, and the picture quality will be deteriorated. For example as for the solid image capturing device, even when the error picture image data does not exist in the continuous plural pixels originally, the error can be spread to the continuous plural pixels by the clock phase of the analog to digital conversion device or the characteristic of the pre-filter set in front of the analog to digital conversion device. In order to avoid this picture quality deterioration problem, a video camera must employ a defective pixel free solid image capturing device or a solid image capturing device with very few defective pixels. However, it is difficult to obtain enough yields in the current manufacturing process technology for the solid image capturing device with a number of pixels used for the high-definition television. This difficulty becomes a big factor that precludes the reduction of the manufacturing cost for the high-definition television camera.
Therefore, with the foregoing in mind, it is an object of the present invention to provide the solution for the above-mentioned problem and to provide an error picture image data correction apparatus that can correct the error picture image data and suppress the image quality deterioration when there are plural error data in the continuous plural pixels and the data around the error picture image data are high frequency signal data.
In order to achieve the above objects, an error picture image data correction apparatus of the present invention comprises an input part for inputting plural picture image data, a selector for selecting a first picture image data and a second picture image data respectively, an error correction part for replacing error picture image data with error correction data on the condition that the first picture image signal at time i is described as x(i), the second picture image signal at time i is described as y(i), t represents time width, n greater than 1, n greater than k greater than 0, n and k are integers, and error data are x(i), x(ixe2x88x92t), x(ixe2x88x922t), . . . , x(ixe2x88x92(nxe2x88x921)t), the error data x(ixe2x88x92kt) is replaced with the error correction data calculated by Equation 3 or its approximate equation.
y(ixe2x88x92kt)+{(nxe2x88x92k)x(i+t)+(k+1)x(ixe2x88x92nt)xe2x88x92(nxe2x88x92k)y(i+t)xe2x88x92(k+1)y(ixe2x88x92nt)}/(n+1)xe2x80x83xe2x80x83(Equation 3)
According to the error picture image data correction apparatus of the present invention, the error picture image data correction can be achieved and the improvement of the picture quality can perform by canceling the deterioration of the picture quality caused by the error picture image data when the error picture image data exist in continuous plural pixels and the picture image data around the error picture image data are high frequency picture image data.